 That's one of the greatest graphics of all time is Napoleon's March on Moscow. It shows the temperature. It shows the relative geography of where they were and how many troops were left at each stage of that campaign. Both there and the retreat, the slaughter of troops by cold weather was unfathomably bad. And you could ice skate on the Thames in London. You could ice skate on it, and you can't now. So we're much warmer than the medieval cool period, right?